Community composition of demersal marine fishes on the Canadian Beaufort Shelf and at Herschel Island, Yukon Territory

• Distinct shallow (< 50 m) and deepwater (< 50 m) marine fish assemblages were detected in the nearshore Beaufort Sea.
• Small subsets of marine species defined the assemblages, whereas other species (e.g., Arctic Cod) were more ubiquitous.
• Variability in fish community structure and abiotic parameters appeared to be highest amongst shallow (< 50 m) sites.
• Depth and salinity best grouped the sites in a manner consistent with species’ abundances on the Canadian Beaufort Shelf.

This study examines the community structure of demersal marine fishes on the Canadian Beaufort Shelf and at Herschel Island, Yukon Territory. Fishes were sampled along five transects during the summers of 2006–2009 to assess community structure. Environmental parameters were documented to examine habitat associations of fishes. Results indicate a shift in community composition at approximately 50 m depth in both areas, forming distinct shallow and deepwater assemblages. A subset of species define the assemblages, with Gymnocanthus tricuspis and Ulcina olrikii typifying the < 50 m and > 50 m groups, respectively, on the shelf. At Herschel Island, U. olrikii did not typify the > 50 m group, suggesting differences in species composition relative to Canadian Beaufort Shelf transects. However, differences in community composition between the two areas were not statistically significant. Boreogadus saida were common to shallow and deep assemblages. Depth and salinity best grouped the sites in a manner consistent with species' abundances on the Canadian Beaufort Shelf. Attempts to match biotic data with environmental parameters at Herschel Island stations were not conclusive. Investigation is required into the role of larger scale processes (e.g., upwelling events, ice-scouring, and plume dynamics) in driving the distributions of marine fishes in the Beaufort Sea.